"Now that Linux is the most popular free Unix-like operating system, it shouldn't be a surprise that some projects have begun treating non-Linux operating systems as second-class citizens. This isn't out of contempt for the BSDs or OpenSolaris, it's just a matter of limited manpower: if almost all the users of the application have a Linux operating system and if all the core developers are using Linux themselves, it's difficult to keep supporting other operating systems. But sometimes the choice to leave out support for other operating systems is explicitly made, e.g. when the developers want to implement some innovative features that require functionality that is (at least for now) only available in the Linux kernel."